In the prior art, various methods and apparatus have been proposed for the sterilization of medical and dental instruments. In general, these sterilization techniques use steam and/or a vacuum to purge the air from a chamber containing articles to be sterilized and steam to heat the load for sterilization. One way such sterilizations are performed is through the use of autoclaves. One type of an autoclave is a relatively large sealed vessel which contains a quantity of boiling water under pressure. The boiling water is used to purge air from the interior of the vessel. In other autoclaves, vacuum is also used for purging. In either instance, problems can develop through imperfect air purgings, and build-up of contaminants from the instruments on the walls of the autoclaves. These autoclaves are also inherently slow in sterilizing due to the large heat capacity of their heavy walls and support structures.
The apparatus disclosed in U.S. Pat. Nos. 5,271,893, 5,290,511 and 5,571,476 to Newman (hereby incorporated by reference in their entirety) overcome many of the disadvantages of conventional autoclaves. These patents disclose a steam purging and sterilization method and apparatus that employ a cassette for sterilization. Through use of the cassette, no transfer from the interior of a sterilization chamber to an auxiliary carrying tray or other post-sterilization handling, of the kind necessary with conventional autoclaves, is involved. The Newman patents also employ a small lightweight unit that is readily adapted for use in an office environment.
While the cassette-using apparatus taught by the Newman patents offer significant advantages over conventional steam purging/sterilizing autoclave techniques, these cassettes are not adapted to use vacuum as part of the steam sterilization process. In addition, these cassettes are not-designed for storing sterilized instruments.
Further, regardless of the apparatus and methods being employed, there is an ever-increasing demand for shorter steam sterilization cycles in the industry.
As such, there is a need for improved sterilization equipment for use in sterilization apparatus and methods, and particularly, equipment enabling faster sterilization times. The present invention responds to these needs by providing a cassette for use in a sterilization method and apparatus employing both vacuum and steam and one that is adapted to store sterilized instruments over time.